The ATF Says It’s Finally Tackling 3D-Printed Machine Gun Converters, or MCDs

Ghost guns, or 3D-printed guns, have been an issue for a while now. VICE has been covering them for over a decade. In that time, the technology that enables anyone to print the individual pieces of a homemade gun to create an untraceable weapon has only become more accessible. A couple years ago, Keegan Hamilton 3D-printed his own Glock and even entered into a ghost gun shooting competition. 

Now, the ATF is finally starting to crack down on an offshoot of the 3D-printed gun market: MCDs, short for machine gun conversion devices.

ATF Director Steven Dettelbach and Deputy Attorney General Lisa Monaco recently announced new initiatives aimed at curbing the proliferation of MCDs, also known as “switches” or “auto sears.” The ATF said MCDs are the most frequently recovered type of illegal firearm.

MCDs can look like innocuous objects—a bottle opener or a Lego block—but are used to convert semi-auto guns into efficient full-auto weapons of mass death. All it takes to print one is about 40 minutes and 40 cents of materials.

Here’s how it works:

The new initiative will create a new Department of Justice committee that will oversee the development of new strategies to take on the devices, train law enforcement officials, and prioritize legal cases involving MCDs. The ATF is also trying to work closely with the manufacturers of 3D printers to find ways to stem the tide. Thousands of these devices are already in circulation.

According to USA Today, the devices have already been used in shooting cases around the country, like in a 2022 mass shooting in Sacramento that left six dead and 12 wounded, as well as the 2023 death of a police chief in Pennsylvania, where the shooter used a pistol with an extended bag and any legal conversion kit.